Coil pick-up and tube recorder system



ay 3 1967 E. e. VOZEOLAS ETAL 3,322,397

COIL PICKUP AND TUBE RECORDER SYSTEM 2 Sheets-Sheet 1 Filed Feb. 25,

YP ATTORNEYS RECORDER OR AMPLIFIER May 30, 1967 E. G. VOZEOLAS ETAL COIL PICK UP AND TUBE RECORDER SYSTEM Fil ed Feb. 25, 1963 2 Sheets-Sheet z R ECORDER REC/ORDER 2 '07 INVENTOR. d 595 E L G VO Z EO LAS SOURCE ARTBZPUR G. VOZ EOLAS ATTOR NEYS United States Patent 3,322,897 C011. PICK-U1 AND TUBE RECORDER SYSTEM El G. Von-Bolas, 86 Pentncket Ave., and Arthur G. Vozeolas, 17 Lawn Ave., both of Lowell, Mass. 01352 Filed Feb. 25, 1963, Ser. No. 260,728 4 Claims. (Cl. 179-1) This invention relates to an improved induction coil pick-up and tube type recorder system especially for instantly and accurately reproducing incoming signals in a telephone hand set.

The conventional transistor type tape recorder now in use is usually not sufficiently rugged, versatile, easily serviceable and dependable to be suitable for daily business recording. The tube type tape recorders, now in use, while well adapted for otfice or business, have the disadvantage that the motor and tubes are energized by the same circuit. Thus keeping the tubes in instant readiness for use requires constant running of the motor and running the motor only when required, involves repeated warmup periods for the tubes from off to on, each of ten to twenty seconds. For example, in a busy pharmacy, wherein it is desired to record a doctors telephoned prescription, to avoid mistakes, the first few sentences are lost while the tubes of the recorder warm up.

The conventional inductive pick-up coil, now in use, is provided with a metal core and is usually detachably mounted on the receiver end of the telephone hand set. However, such metal core type, inductive, pick-up coils usually require tuning, often by changing the position of a relatively insecure and bulky attachment to the hand set so that the various commercial units available leave much to be desired as far as signal output, signal to noise ratio, noise level, clarity of voice, predictable performance, method of attachment and physical appearance are concerned. Such devices have been located in one segment of a 360 rubber ear muff slipped over the receiver cap of a hand set as in US. Patent 2,820,846 to Hansen of Jan. 21, 1958, or attached by a clip in a similar segmental position as in US. Patent 2,005,973 to Hellmann of June 25, 1935, but more often have been mounted coaxially in advance of the cap as typified in U.S. Patent Re. 22,198 to Loewe of Oct. 6, 1942 or US. Patent 1,928,669 to Lybarger of Oct. 6, 1933.

A metal core, inductive, pick-up coil mounted in advance of the receiver end of a hand set has the metal diaphragm of the hand set interposed between the receiver coils and the pick-up coil, thereby affecting the magnetic lines of force of the magnetic flux of the coils. It also picks up only a small portion of this magnetic fiux. A metal core, coil, occupying only a segment of the 360 surrounding the telephone receiver coils, picks up only a fraction of the field created by the magnetic flux of the coils and the cylindrical shell holding the receiver coils usually is rotatable, rather than fixed within the hand set, thereby requiring delicate positioning and tuning adjustment of the pick-up device.

One object of this invention is to provide an inductive pick-up coil connectable to the input of a sound recorder, the coil having an air core for receiving the elongated housing of a sound reproducer housing and being mounted around the housing in a plane normal to the axis thereof.

Another object of the invention is to provide improved circuitry in a tube type sound recorder wherein a switch initially energizes the amplifier tubes at reduced voltage without energizing the motor and a second switch energizes the tubes at full voltage while energizing the motor.

A further object of the invention is to provide an improved sound recording system which combines an annular, air core pick-up coil on a telephone hand set with a stand-by heating circuit in a tube type sound recorder whereby, for example the first few words of a telephone conversation can be faithfuly and instantly recorded without warm-up delay or tuning.

Still another object of the invention is to provide a compact, air core pick-up coil having an air core adapted for 360 positioning, and a 360 magnetic flux pick-up around the elongated coil housing of a telephone hand set, loudspeaker or the like, the coil not requiring tuning because it is entirely and symmetrically within the flux surrounding the housing and shields the same from extraneous electric impulses such as 60 cycle hum, eX- traneous electrical noise impulses, while increasing signal pick-up, etc.

A still further object of the invention is to provide an annular, air core, inductive pick-up coil detachably mounted around the receiver end of a telephone hand set just in rear of the threaded cap, or substantially so located so as to be coaial with and normal to the central longitudinal axis of the magnetic core members of the hand set, the pick-up coil having a predetermined number of windings, inside core diameter, magnetic wire diameter and width to achieve optimum elficiency.

Other objects and advantages of the invention will be apparent from the claims, the description of the drawings and from the drawings in which:

FIG. 1 is a fragmentary, half sectional side elevation of the receiver end of a telephone hand set with a pickup coil of the invention mounted thereon;

FIG. 2 is a similar view showing the pick-up coil in half section, another embodiment of the mounting means and dotted lines of flux;

FIG. 3 is an enlarged, side sectional view of the flange type mounting means;

FIG. 4 is a view similar to FIG. 3 showing the deformable rubber-like cushion mounting means;

FIG. 5 is a fragmentary front view on line 5-5 of FIG. 1;

FIG. 6 is a diagrammatic side elevational view, in half section, showing the pick-up coil of the invention positioned around the voice coil in a loud speaker, an alternative position of the coil being shown in dotted lines;

FIG. 7 is a fragmentary view, similar to FIG. 1 showing coil mounting means in the form of a conventional rubber-like ear muff;

FIG. 8 is a diagrammatic view of the sound recording system of the invention showing the equalizer circuit, the selective recorder switch and the improved recorder circuit for avoiding tube warm-up delay.

The preferred embodiment of the sound recording system 25 of the invention is shown diagrammatically in FIGURE 8 wherein a conventional telephone hand set 26 and conventional tube type sound recorders 27 and 28 are illustrated.

As best shown in FIGURE 1 the receiver end 30, of hand set 26, includes the male rim threads 31, upon which a threaded cap 32 is mounted, the peripheral rim 33 of the cap normal-1y abutting on the annular shoulder 34 of the end 30. An internal shoulder 35, within the end 30, seats the cylindrical shell 36 which carries the diaphragm 37 and magnetic pole members 38 and 39 by which incoming electric signals from conductors 41 and 42 are converted to sound vibrations. The shell 36 constitutes a magnetic sound reproducer and is rotatable within an elongated, cylindrical recess 43 within a substantially, cylindrical housing 44 formed by the plastic material of the end 30, rim threads 31 and rim 33 of the cap, the housing 44 having a central longitudinal axis indicated at 45. The magnetic pole members 38 and 39 are symmetrically disposed relative to axis 45, on each opposite side thereof, but slight rotation of the shell 36 within the recess 43 will tend to rotate the magnetic flux lines therearound from one segment of 360 to another segment of 360 around the axis. Diaphragm 37 is usually of metal and is normal to the axis 45 and the magnetic pole members 38 and 39 are positioned just in rear of the threaded cap 32 from an axial point of view.

The inductive pick-up coil means 48 includes the annular induction coil 49 formed of multiple convolutions of magnetic wire 50 with an air core 51, the inside diameter of the annular coil being adapted to receive, and fit over, the elongated housing 44. For optimum efliciency the coil 49 preferably comprises about fifteen hundred convolutions, or turns, of No. 40 magnetic wire, although it will be obvious that, in applications other than on a conventional, present day telephone hand set, the number of turns, diameter of the air space 51, size of wire and physical configuration of the coil may be varied by one skilled in the art to suit the requirements of the application. Preferably the coil 49 is about one quarter inch wide, relatively flat and provided with an annular, tubular, shielding cover 52 of flexible sheet material such as plastic. The coil 49 terminates in a flexible shielded electric conductor 53, having an insulative covering 54 and terminating in a male connector 55 adapted to be plugged into a sound recorder to connect the coil 49 to the input of a recorder or amplifier.

The annular, air core inductive pick-up coil 49 is secured on the exterior of the housing 44 at the receiving end 30 of hand set 26 by mounting means 58 so that it is carried by, and is movable with the hand set. Preferably mounting means 58 includes an inwardly projecting, annular flange 59 on the forward face 60 of the cover 52, the flange fitting over and around the rim threads 31 and being detachably clamped in position against shoulder 34 by the rim 33 of threaded cap 32. The flange 59 thus positions the coil in 360 encircling position around the housing 44 just in rear of the threaded cap 32, and in alignment with the magnetic pole members 38 and 39.

The plane of the coil is normal to the axis 45 and parallel to the diaphragm 37 and the entire coil envelops and shields the coil portion of the sound reproducer shell 36 to be entirely within the magnetic flux thereof regardless of rotation of the shell. Flange 59 is preferably part of an element 61, of right angular cross section and of metal, or plastic material, the cylindrical wall portion 61 thereof if of metal, being grounded as at 63 for shielding the coil from 60 cycle hum, extraneous electric impulses and other noise factors, thereby resulting in a desirable low noise to sound ratio.

It is believed well known that the magnetic lines of force emerge from the north poles of pole members, such as 38 and 39, pass through the surrounding medium, which is the material of shell 36, the material of hand set 26 and the ambient air therearound, to reenter the south pole of pole members 38 and 39 to form a closed magnetic loop, or closed magnetic circuit. It is believed that the flux density in the central portion of the medium surrounding the pole members 38 and 39 is prefer-able to the flux density at each opposite end of the pole members 38 and 39 for inductive pick-up of signals and the pick-up coil 49 is detachably located in that position on the hand set 26.

As shown in FIGURE 4, the mounting means 58 may be in the form of an annular cushion 64 of flexible, resilient, deformable material such as rubber, sponge plastic or the like, the outer face 65 of the cushion being firmly secured by a layer of adhesive 66 to the inner face 67 of the cover. The coil 49, element 61 and flange 59 may be retained, if the inside diameter thereof is slightly increased, or as shown in FIGURE 2 parts may be just large enough to slip over the threaded cap 32 with the cushion conforming to the shape of the housing 44 just in rear of the cap.

As shown in FIGURE 7, a commercially available rubber-like ear muff 68 may also be used as mounting means 58, the rear face 69 thereof being secured by a lsazyer of adhesive 70 to the forward face 60 of the cover In FIGURE 6 the annular, inductive pick-up coil means 48, with its air core coil 49, shielding cover 52, conductor 53 and mounting means 58 is shown in 360 encircling position around the elongated sound reproducer housing 72 of a typical loud speaker .73. The coil 49 is parallel to the spider 74 of the cone 75 and in a plane normal to the central longitudinal axis of the voice coil 76. While a position encircling the voice coil gives the best results, for practical purposes to avoid entrance into the cabinet 77, a hook 78 or equivalent support means, is provided on the face of the cabinet, by which the coil 49 may be suspended by its conductor 53, coaxially in advance of the cone.

In FIGURE 8 the annular air core pick-up coil means 48 is shown secured in position on the receiver end 30 of a telephone hand set 26 as heretofore described. The plug connector 55 connects to the armature 80 of the selector switch 81, switch terminal 82 and conductor 83 leading to the input of recorder 27 and switch terminal 84 and conductor 85 leading to the input of identical recorder 28. An equalizer circuit 86 including a resistor 87 and a capacitor 88 is shown diagrammatically at a convenient location between the pick-up coil and the amplifier, to permit adjustment, the resistor being fixed or variable as desired.

Since recorder 27 is identical with recorder 28 only the pertinent circuitry of the latter is shown diagrammatically. The tube type recorder 28 includes the conventional amplifier tube circuit 90, powered by the secondary 91 of a transformer 92, the primary 93 and the motor 94. It has heretofore been customary to include the primary 93, the motor 94 and the source of current 95 in a circuit whereby closing of the circuit causes the motor to be energized during the ten or twenty second tube warm-up period.

In the system of this invention, a first circuit 97 is provided including source 95, primary 93, variable resistor 98, and a first switch 99. Resistor 98 permits a reduced standby voltage to energize primary 93 when switch 99 is closed to maintain the tubes in the amplifier circuit 90, in standby condition of readiness, thereby eliminating initial warm-up time. The first circuit 97 does not include motor 94. A second circuit 101 is provided including the source 95, primary 93, first switch 99, motor 94 and a second double pole switch 102, the second circuit bypassing the variable resistor 98 to permit full voltage to energize the amplifier tube circuit when switches 99 and 102 are both closed.

In operation the switches 99 of both recorders are initially closed to place the tubes in standby condition. Armature 80 of selector switch 81 is moved to one terminal such as 84 to connect with the input of one recorder such as 28. Upon receipt of a call on handset 26, switch 102 of recorder 28 is closed thus instantaneously energizing motor 94 and raising primary 93 to full voltage so that the first words of the conversation inductively picked up by coil 48 can be recorded. When the tape of recorder 28 is full, armature 80 of selector switch 81 is moved to terminal 82, the switch 102 of recorder 27 is closed and recorder 27 is then ready to record the first words of conversations on hand set 26.

The standby system, or circuit, of the invention reduces heat in the amplifier circuit, and reduces wattage therein, in a noticeable amount. For example, in a conventional recorder the amplifier normally consumes about 22 watts and the motor about 15 watts, totalling 37 watts. In the standby circuit described herein, the motor consumes no wattage, the amplifier circuit consumes only about 10 watts and the resistor 98 dispenses the remaining 12 watts. The reduced wattage in the amplifier circuit conserves the life of the tubes, condensers and resistors therein and reduces heat. It has been found that a resistor 98 of about 25 watt capacity, or more, easily absorbs the 12 watts without unduly creating heat,

Resistor 98 may be fixed in which case it reduces the voltage by about 20-30% to provide instant action, or if variable, it will normally be set to supply about seventy percent voltage or above. While a diode can be used in place of resistor 98, it will supply only about half voltage and require two to four seconds warm-up time.

A capacitor 108 may be provided in second circuit 101, between conductor 114 and armature 112 to reduce arcing.

In the system of FIG. 8 it will be apparent that either recorder can be used at will, regardless of the amount of tape remaining, by merely shifting the selector switch 81. It Will also be obvious that the movement of armature 80 of selector switch 81 can be automatic by the use of suitable relays to move the armature 80 to the appropriate switch terminal and vice versa.

In detail first circuit 97 includes the source 95, conductor 103, primary 93, conductor 104, variable resistor 98, conductor 105, armature 106 of switch 99 and conductor 107. Second circuit 101 includes source 95, conductor 103, primary 93, conductor 104, conductor 109, armature 110 of switch 102, conductor 111, armature 112 of switch 102, conductor 113, conductor 114, armature 106 of switch 99 and conductor 107.

While the system of this invention has been shown and described herein, in what is believed to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention without departing from the spirit of the invention and that the invention is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims.

We claim:

1. In combination with an electrically operated sound reproducer of the type having a housing with a central, longitudinal axis, magnetic pole means symmetrically disposed relative to said axis within said housing, a dia-' phragm normal to said axis and an electric conductor for enabling said means to receive incoming electric signals and actuate said diaphragm;

an annular, air core, induction, pick-up coil formed of multiple convolutions of a magnetic Wire terminating in a flexible conductor leading therefrom and adapted to be connected to the input of a recorder or am plifier, the air core of said coil being of sufiicient diameter to receive, surround and completely encircle the exterior of said housing intermediate of the opposite poles of said magnetic pole means and mounting means detachably securing said coil in 360 encirclement position on, and closely fitting around, said housing, the plane of said coil being substantially parallel to the plane of said diaphragm, normal to the central longitudinal axis of said magnetic pole means and intercepting said magnetic pole means, said coil being entirely within, centrally of, and symmetrically disposed relative to, the 360 magnetic flux, and closed magnetic loop, sourrounding said magnetic pole means.

2. A combination as specified in claim 1 wherein said sound reproducer is a telephone hand set having rim threads and a threaded cap on the receiver end thereof,

said coil includes an annular, tubular, shielding cover,

and

said mounting means is an annular element of right angular cross section partially enclosing said cover and having an annular flange projecting inwardly from the forward face of said cover and fitting the rim threads at the receiver end of said hand set in rear of said threaded cap.

3. A combination as specified in claim 1 wherein said sound reproducer is a telephone hand set having a threaded cap on the receiver end thereof;

said coil includes an annular, tubular shielding cover,

said mounting means is an annular cushion of flexible resilient material having an external periphery anchored to said cover and having an external periphery adapted to yieldably fit over the exterior of the receiver end of said hand set just in rear of said threaded cap.

4. An annular induction pick-up coil formed of multiple convolutions of a magnetic wire terminating in a flexible conductor leading therefrom and adapted to be connected to the input of a recorder or amplifier,

said coil having an air core and an inside diameter adapted to receive and surround with a relatively close fit the exterior of the elongated housing of a magnetic sound reproducer, and

mounting means on said coil for detachably securing the same on the exterior of said housing without damaging the same, in 360 encirclement position relative to, co-axial with, and in a plane normal to, the central longitudinal axis of said housing,

said mounting means comprising an annular element of right angular cross section, partially enclosing said coil and having an inwardly projecting annular flange with a predetermined inside diameter adapted to fit the male rim threads at the receiving end of a telephone hand set in rear of the threaded cap thereon.

References Cited UNITED STATES PATENTS 982,641 1/1911 Steinberger 179-187 2,268,665 1/1942 Loewe 179-1 FOREIGN PATENTS 110,721 6/1940 Australia. 805,392 12/ 1958 Great Britain.

KATHLEEN H. CLAFFY, Primary Examiner. R. MURRAY, Assistant Examiner, 

1. IN COMBINATION WITH AN ELECTRICALLY OPERATED SOUND REPRODUCER OF THE TYPE HAVING A HOUSING WITH A CENTRAL, LONGITUDINAL AXIS, MAGNETIC POLE MEANS SYMMETRICALLY DISPOSED RELATIVE TO SAID AXIS WITHIN SAID HOUSING, A DIAPHRAGM NORMAL TO SAID AXIS AND AN ELECTRIC CONDUCTOR FOR ENABLING SAID MEANS TO RECEIVE INCOMING ELECTRIC SIGNALS AND ACTUATE SAID DIAPHRAGM; AN ANNULAR, AIR CORE, INDUCTION, PICK-UP COIL FORMED OF MULTIPLE CONVOLUTIONS OF A MAGNETIC WIRE TERMINATING IN A FLEXIBLE CONDUCTOR LEADING THEREFROM AND ADAPTED TO BE CONNECTED TO THE INPUT OF A RECORDED OR AMPLIFIER, THE AIR CORE OF SAID COIL BEING OF SUFFICIENT DIAMETER TO RECEIVE, SURROUND AND COMPLETELY ENCIRCLE THE EXTERIOR OF SAID HOUSING INTERMEDIATE OF THE OPPOSITE POLES OF SAID MAGNETIC POLE MEANS AND MOUNTING MEANS DETACHABLY SECURING SAID COIL IN 360* ENCIRCLEMENT POSITION ON, AND CLOSELY FITTING AROUND, SAID HOUSING, THE PLANE OF SAID COIL BEING SUBSTANTIALLY 